Fluid pressure unloader



July 3, 1934. c LIPMAN 1,965,420

FLUID PRESSURE UNLOADBR Filed April 1, 1931 3 Sheets-Sheet l W, MM 9 July 3, 1934. c. E. L. LIPMAN FLUID PRESSURE UNLOADER Filed April 1, 1931 3 Sheets-Sheet 2 y 1934. c. E. L. LIPMAN 1,965,420

FLUID PRESSURE UNLOADER Filed April 1931 3 Sheets-Sheet 3 iii/62w?" Car/EL Zozrzara M W1 MM? Patented July 3, 1934 UNITED STATES FLUID PRESSURE UNLOADER Carl E. L. Lipman, Chicago, 111., assignor to Lipman Patents Corporation, Chicago, Ill., a corporation of Delaware Application April 1, 1931, Serial No. 526,812

6 Claim.

This invention relates to refrigerating systems of the compressor condenser evaporator type.

In this type of refrigerating system, and more particularly in those forms thereof wherein the motor compressor is an hermetically sealed unit, it is desirable, and in some instances necessary, for a proper and successful operation of this system to substantially equalize the pressures upon the high and low sides or unload the motor compressor unit, as it is termed, at starting. It is also desirable in some instances to muflle the discharge from the compressor to insure quiet operation.

The purpose of this equalization is to reduce the resistance to starting of the motor compressor unit and thereby reduce the starting load upon 1' the motor to permit the use of a'motor of minimum capacity for the actual work to be performed during running periods.

.. This feature is particularly desirable in sealed 1 units wherein it is necessary to use a motor of as low capacity and size as possible. It is also necessary, of course, to prevent the relatively warmrefrigerant from passing back through the suction line to the low side and into the evaporator during idle periods or when the pressures upon the high and low sides are equalized to un-' load the unit. Otherwise, the reverse flow of refrigerant will transfer heat to the expansion or evaporating element and result in an appreciable loss in efllciency.

It is, therefore, an object of this invention to provide an unloading means in a refrigerating system operable to materially reduce the pressure in the high side of the system during idle periods of the motor compressor unit in order that the motor compressor unit may be started against substantially no load. It is understood, of course, that the foregoing feature is to be accomplished without permitting reverse flow back of the warm refrigerant through the suction line into the evaporator. v

It is also an object'of this invention to provide such an unloading mechanism operable in response to the operating condition of the motor compressor unit, and consequently, in response to the flow and pressure of the refrigerant fluid in the discharge side of the compressor.

It is a still further object of this invention to provide an unloading mechanism which, if desired, may be incorporated within the sealed container housing the motor compressor unit.

In accordance with this invention the flow of refrigerant and the resulting pressure built up by the operation of the compressor during running periods is utilized to control means for reducing the pressure upon the high side of the system during idle periods of the motor compressor unit.

In the preferred form. although it will be manifest that other constructions may be employed to utilize the principles of this invention, a bypass conduit is connected between the high and low pressure sides of the system in which a valve is placed, the latter being controlled by the movement and pressure of refrigerant being discharged by the compressor. The operating parts are also so arranged that a very small volume of the discharged gas is necessary to operate the unloading mechanism whereby the latter is immediately responsive to variation in the discharge side.

Other and further objects and their accompanying advantages will be apparent as this invention becomes better understood from an examination of the specification and claims in connection with the accompanying drawings wherem:

Fig. 1 is an interior view of a motor compressor unit, certain parts thereof being broken away to illustrate the interior construction and application of an unloading mechanism embodying the principles of this invention,

Fig. 2 is a schematic illustration of a complete refrigerating system embodying a sealed motor compressor unit having incorporated therein an unloading mechanism embodying the principles of this invention,

Fig. 3 is a horizontal section taken on line 3-3. of Fig. 1,

Fig. 4 is a perspective view of the unloading valve and actuating lever,

Fig. 5 is a plan of a modified form of unloading valve and circulating mechanism,

Fig. 6 is a section on line 66 of Fig. 5 showing the interior construction, and

Fig. 7 is a side elevation of the form shown in Fig. 5.

With particular reference to Fig. 1 it will be observed that the motor compressor unit is housed within a dome or shell 1 secured to a base 2. Within the shell and carried by the base is a driving motor 3, connected to a compressor 4, which delivers the refrigerant under pressure into the interior of the dome and the lubricating oil up through the central bore 6 of shaft '7 where it strikes a deflector and separator 8 which causes the oil to drop back down over the motor elements. It will be understood from this that the entire interior of the dome is under the discharge pressure of the compressor, the dome being provided with a fitting 9 to lead off the compressed refrigerant.

In order to reduce the pressure of a high pressure side and substantially equalize the high and low sides of a system prior to starting. a by-pass conduit is provided between the two sides. For this purpose the intake duct 11 is connected to a tube 12 terminating in a valve casing 13 which discharges into the interior of the shell or dome 1. The casing is provided with a needle valve closure member 14 to control the flow through the valve casing. The casing may be conveniently supported upon a bracket 16 secured to the base 2. Valve casing 13 is provided at its upper end with a drip tray 17, arranged to catch a portion of the oil dripping down over the motor elements to provide a seal and lubricate the valve closure element.

The valve element 14 is arranged to be actuated by a lever 18 pivoted at 19 to the bracket 16. One end 21 of the lever interlocks with the upper end of the valve 14, and its opposite end terminates in the pair of yoke arms 22 which circumvent the compressor, and to which is'secured an inverted arcuate cup-like receptacle or float 23. .The lever 18 is designed and arranged so that the float 23 will lie against the interior of base 2 with the valve 14 in open position, in which position the high and low pressure sides will be in communication through the by-pass tube 12 and valve casing 13, the latter opening into the interior of the dome.

A discharge tube 24 is connected from the discharge side of the compressor and extended along the base 2 and into the interior of the inverted cup 23, the end of tube 24 lying within the cup 23 and being perforated as at 26. It will be understood that the cup 26 will be partially immersed within the lubricating oil within the base, the level of which is indicated generally by the line 27. The lubricating oil thus seals the lower open end of cup 23. Cup 23 is provided with a vent hole 23 which will permit escape of refrigerant from within the cup to the interior of the shell and which will also permit the cup to settle down into the oil.

From the foregoing description it will be apparent that when the motor and compressor are in operation a portion of the refrigerant under pressure will be discharged through tube 24 and apertures 26 into the receptacle 23. This flow of refrigerant therefrom under pressure will force the cup upwardly swinging the lever about pivot 19 and closingvalve member 14 upon its seat. This action will .close the by-pass between the high and low sides of the compressor after the motor has been started, following which the motor compressor unit will function in its normal way. If the compressor should stop, the outflow of refrigerant from tube 24 and apertures 26 there will cease and the cup 23 will settle and sw' lever 18 downwardly about its pivot 19, by the action of gravity, raise valve member 14, and thus open the by-pass'between the high and low sides of the compressor to permit substantial equalization of the pressures therein. This will reduce the load upon the compressor at starting, thus permitting the motor compressor to resume normal speed before the by-pass is closed and load is thrown upon the compressor.

Referring particularly to Figs. 5, 6 and '7, there is shown a modified form of this invention in which the unloading mechanism, including the valve and its actuating means, are reduced in size in order that the unloading mechanism may be installed as a unit on the base of the refrigerating apparatus and to one side of the pump and motor instead of encircling the same. In this form of unloading mechanism the actuating shell is also provided with an inner member whereby the volume of gas necessary to actuate the unloading valve is reduced to a. minimum, whereby the actuating float or shell is responsive to minute variations in the condition of the dischargegas.

As in the previous form, the by-pass duct or tube 12 is connected to a valve casing 41 which discharges into the interior of the shell or dome 1. The valve casing is provided with a needle valve closure member 42 to control the flow through the valve casing. The casing may be conveniently supported upon a base 43 and is provided at its upper end with a drip tray 44 arranged to catch a portion of the oil d ip 4 down over the motor elements. This'oil provides a seal for and lubricates the needle valve 42. The drip tray is provided with a pair of cars 46 which serve as bearings for a pivot pin 47 for the lever 48. One end 49 of the lever interlocks with the upper end of valve 42 to raise and lowerthe same, whereas the other end 51 of lever 48 carries an inverted cup-like shell or receptacle 52. This latter member functions as a float to actuate lever 48 as will be explained. Within the shell 52 is a hollow displacement cup 53 sealed at its bottom by the base 43. Depending within the displacement cup is a short tube 54 which extends upwardly through the top of the cup and downwardly to approximatelywthe bottom thereof. The discharge tube 24 from the compressor is brought in through the base 43 and discharges through its terminating end 56 into the interior of the displacement cup 53 from which the discharged-refrigerant may pass upwardly through tube 54 into the interior of float 52 and from there into the dome 1.

The operation of the form illustrated in Figs. 5 and 7 is substantially the same as that previously described, that is, the refrigerant discharged from the condenser passing out through tube 24 will enter the interior of the displacement cup 53 and from thence into the space between displacement cup 53 and float or shell 52. The pressure of the discharged refrigerant will thus act upon the shell to seat valve 42 when the compressor is running. The converse is, of course, true, that is, when the compressor is not running shell 52 will fall to its lower position and open valve 42 to unload the compressor. 3

By providing the hollow displacement cup instead of a solid member, the noises due to discharge of the refrigerant are muffled and the machine made substantially noiseless in operation. Any lubricant which is carried over with the refrigerant will lie in the bottom of the displacement cup and seal the lower end of tube 54, thus further insuring quietness of operation. Should the oil collect in undue quantities it will be passed in small quantities through tube 54 and thus return to the base of the refrigerating unit.

Referring particularly to Fig. 2, the complete refrigerating system is illustrated as embodying a motor compressor unit enclosed within a shell 1 and mounted upon a base 2 which delivers refrigerant through theconnection 9 into a refrigerant circulatory system through discharge pipe 29 into the condenser 31 which liquefies the same and delivers it into float chamber 82. From the float chamber 32 the refrigerant passes through a liquid line 33 into the cooling unit or evaporator 34. From the evaporator 34 the vaporized refrigerant is withdrawn through the suction line 36, which includes a check valve 37, to prevent reverse flow of refrigerant through the suction line, and into the evaporator. In the system illustrated, a portion of the lubricating oil, at least, is circulated through an oil cooler 38 by means of connecting pipes 39.

From the foregoing disclosure, it will be apparent that there has been provided an unloading device which is particularly well adapted to be included within the sealed motor compressor unit and which is operative in response to the operating condition of the motor compressor unit which consequently causes the unloading mechanism to be responsive to the flow and pressure of refrigerant in the discharge side of the compressor.

It is obvious that changes may be made in the connections and in the details of construction without departing from the spirit and scope of this invention as defined in the appended claims.

I claim:-

1. A motor compressor unit adapted to be operated intermittently comprising a compressor, a motor for driving the same, and means for unloading the compressor including a by-pass between the high and low pressure sides of the compressor, a valve in said by-pass, a lever and a movable element connected to said lever and disposed in the path of the discharge fluid from said compressor, said lever being operatively connected to said valve to actuate the latter in accordance with the flow of discharge from said compressor when running and operable by gravity to substantially equalize the pressures in the high and low pressure sides of the compressor when the latter is idle.

2. A motor compressor unit adapted to be operated intermittently comprising a compressor,

a motor for driving the same, and means for unloading the compressor including a by-pass between the high and low pressure sides of the compressor, a valve in said by-pass, an inverted float arranged to receive a portion of the discharge fluid of said compressor, and connections between said float and said valve for operating the latter against the action of said fluid to substantially equalize the pressures in the high and low pressure sides of the compressor when the latter is idle.

3. A motor compressor unit adapted to be operated intermittently comprising a compressor, a motor for driving the same, means for unloading the compressor including a by-pass between the high and low pressure sides of the compressor, a valve in said by-pass, an inverted float arranged to receive a portion of the discharge fluid of said compressor, means for sealing the open end of said float, and connections between said float and said valve for operating the latter by gravity to substantially equalize the pressure in the high and low pressure sides of the compressor when the latter is idle.

4. A motor compressor unit adapted to be operated intermittently comprising a compressor, a motor for driving the same, means for unloading the compressor including a by-pass between the high and low pressure sides of the compressor, a valve in said by-pass, an inverted float arranged to receive a portion of the discharge of said compressor, a displacement member within said inverted float, and connections between said float and said valve for operating the latter to open said valve and substantially equalize the pressures in the high and low pressure sides of the compressor when the latter is idle.

5. A motor compressor unit adapted to be operated intermittently comprising a compressor, a motor for driving the same, means for unloading the compressor, including a by-pass between the high and low pressure sides of the compressor, a valve in said by-pass, an inverted float connected to said valve for actuating the latter by gravity to substantially equalize the pressures in the high and low pressure sides of the compressor when the latter is idle, and a hollow displacement member within said float arranged to receive the discharge from said compressor, said hollow displacement member having an opening therethrough leading into the interior of said float.

6. A motor compressor unit adapted to be operated intermittently comprising a compressor, a motor for driving the same, and means for equalizing the pressures in the high and low sides of the compressor during idle periods of the compressor, said means including a connection between said high and low sides, a valve controlling communication through said connection, and means including a float adapted to be actuated by the pressure in the high side for closing'said valve under the influence of said pressure, said float being provided with a restricted pressure relief opening permitting delayed gravity actuation of said float for opening said valve upon cessation of pressure delivery by said compressor.

CARL E. L. LIPMAN. 

